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Full text of "The manufacture and properties of iron and steel"

542                                      THE IRON INDUSTRY.
plants working on structural shapes, at the time of my visit in 1899, the chaotic condition of the hot bed and cold bed and loading department was something which cannot be described. This branch of rolling-mill work is the weakest feature of German practice, while the operation of heavy blooming and reversing mills is the strongest.
The output of acid Bessemer steel is small, being only one-tenth of the basic tonnage, and the acid open hearth contributes only one-tenth as much as the basic furnaces. Half the steel is made in the large steel plants, meaning by this that they operate- both blast furnaces and a Bessemer plant, while the rest was made in small plants and steel-casting works, the latter having 21 furnaces averaging 9 tons each.
I am informed by Mr. Schrodter that "there are several works which turn out 32,000 to 35,000 tons in a month, from either two or three basic converters of 18 to 20 tons capacity, using one vessel at a time." I have received personal communications from four German works giving me the output of their converters. The first four plants are in the Euhr district, while Rothe Erde is at Aachen.
Size of        Tons per month
Works.                                                             converter.       per converter.
Phoenix____.................................         12& tons           7,000
Hoesca......................................         11 tons              8,000
Horde........................................         18 tons              8,000
Rheinische...................................         15 tons              6,500
RotheErde..................................         15 tons              7,500
A basic lining in a converter is considered to do well if it lasts 220 heats, while the bottoms average 45 to 50 heats. It is the practice to run one vessel at a time, and this will make three heats per hour, since the time of blowing is about twelve minutes. Every sixteen hours the bottom must be changed, while delays occur from repairs to tuyeres. When such a delay does occur, another vessel is brought into use until the repairs are completed. Sometimes the vessels are used alternately when the iron is blowing hot, and sometimes heats are made out of turn to keep the lining hot on an idle vessel, as a basic lining suffers from becoming too cold. At the end of three days the first vessel will be worn out and relining takes fifteen hours and firing about six hours more. While this is going on the second and third vessels must be working and there are many times when a fourth unit is needed, the newest plants being designed on this basis. The output will not increase in proportion to